Trauma “Re-wires” Your Brain Part 2: The Hippocampus

In part 1 I began this trauma discussion with the oldest and most primal part of the brain, commonly known as the reptilian brain. It is responsible for survival (fight, flight or freeze). In part 2 I will tell you a little about the next portion of the brain to evolve and can be visualized as the second layer of the brain (going inside out). This second layer is commonly known as “the Mammalian Brain” as it is only found in mammals. The mammalian brain gives us the ability to have memories, emotions, and judgements.

Within the mammalian brain there is a section called the “Hippocampus”. The hippocampus helps us to make sense of emotions (empathy) and place them in a timeline. We are born with the amygdala fully developed, providing us with the basic techniques for survival. The hippocampus, however, does not fully develop until around ages 2-3. This prevents infants from being able to place their experiences on any kind of timeline, rendering them incapable of developing conscious memory until the hippocampus is fully formed. It is important to note that conscious or explicit memory is different from unconscious or implicit memory.

“Explicit memory involves facts, descriptions, and operations that are based on thought; implicit memory involves procedures and internal states that are automatic”

(Rothschild, B. (2000). Development, Memory, and Brain. In The Body Remembers: The Psychophysiology of Trauma and Trauma treatment. New York, New York: Norton.)

An example of implicit memory is knowing how to ride a bike. It is a memory held in the body not in your conscious mind. Implicit memory is able to be stored well before ages 2-3, re-affirming the importance of forming healthy attachments at a young age.

Returning once again to trauma, one of the functions of the hippocampus is empathy. With individuals who do not have what is called “trauma brain”, the hippocampus is the first place information is processed, encouraging connection with others. If you are an individual who has a larger amygdala due to multiple traumatic experiences over a period of time, the hippocampus is the last place you process information. For those with a brain wired to expect trauma, due to the continual exposure, all information is processed through the amygdala first. These are the individuals who are always expecting the floor to be pulled out from under them.

In summary, most individuals process information and other external stimuli through the hippocampus first, taking emotions and feelings into account and looking for ways to make connections. The individuals whose brain has been wired to expect trauma have a larger amygdala and process information through the amygdala first. These people’s brains are trained to assume everything is a threat first and foremost. To conclude this series, the next blog will speak about the most recently developed part of the brain, the human brain, and what role it plays.

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2 Replies to “Trauma “Re-wires” Your Brain Part 2: The Hippocampus”

So thru therapy or self awareness how can the hippocampus become the primary part for cognitive reasoning over reactionary use of the amygdala. Is it possible to quiet or bypass the amygdala in situations that don’t normally cause most people to over react to.

Great question and yes it is possible, however it has to be undone the same way it was done, if that makes sense. We are finding more and more evidence of the neuroplasticity (ability to change) of the brain over the life span.

Just like trauma wired the brain to process information through the amygdala first, it has to be Re-wired to process information through the hippocampus first. That is done most effectively through talk therapy over a long period of time. Regardless of what therapeutic intervention is used, it is through the therapeutic relationship that healing comes. A trauma brain has to develop a healthy and secure attachment with someone that can be trusted to stay solid even when it feels like the whole world is collapsing.

I hope that answered your question and please feel free to contact me for further clarification!